InfoPath Dev

I have a SharePoint 2010 list that has a field with Rich text. How can I change it without deleting the field and re-adding it? If I delete it I will lose all the data currently in there.

Is your issue with a SharePoint List, or promoted fields from an IP form? If SharePoint, not the forum, but you could convert the field in the list settings to plain text. If you can't convert the field in the form and you dont want to delete it, You are going to have an issue and could lose existing data. You could try creating another field (text only) and set it equal to your rich text. also there is a setting on the display tab, I believe that will allow you to remove some rich functionality, at least in 2010. Another method which is laborious.

add the text field that will replace

promote both fields and make sure they are editable in sharepoint

open library in data sheet view and copy text from rich field to plain text field.

then you could delete the ricj field.

this will show all items modified by you. Also any workflows could trigger.

You can just change the column type in SharePoint from rich text to plain text and it will strip all of the formatting without losing the data.  Did you try it and your data was lost?